package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;
    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }


    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    /**
     * Redis穿透
     * @param keyPrefix
     * @param id
     * @param type
     * @param dbFallback
     * @param time
     * @param unit
     * @return
     * @param <R>
     * @param <ID>
     */
    public <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        //根据ID在redis中查询
        String Json = stringRedisTemplate.opsForValue().get(key);
        //存在，返回
        if (StrUtil.isNotBlank(Json)) {
            //反序列化
            return JSONUtil.toBean(Json, type);
        }
        if (Json != null){
            return null;
        }
        //不存在查询数据库
        R r = dbFallback.apply(id);
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //存入redis
        this.set(key, r, time, unit);
        //返回
        return r;
    }

    private static final ExecutorService CACHE_REBUILD_POOL = Executors.newFixedThreadPool(10);

    /**
     * Redis击穿 -逻辑过期
     * @param keyPrefix
     * @param id
     * @param type
     * @param dbFallback
     * @param time
     * @param unit
     * @return
     * @param <R>
     * @param <ID>
     */
    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, Long time, TimeUnit unit){
        String key = keyPrefix + id;
        //根据ID在redis中查询
        String Json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(Json)) {
            //redis存在，返回
            return null;
        }

        //不存在，命中，序列化
        RedisData redisData = JSONUtil.toBean(Json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，返回
            return r;
        }
        //已过期，需要重新缓存
        //1.获取互斥锁
        String localKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(localKey);
        if (isLock) {
            //获取成功
            CACHE_REBUILD_POOL.submit(()->{
                //查询数据库
                R r1 = dbFallback.apply(id);
                //写入Redis
                this.setWithLogicalExpire(keyPrefix, r1, time, unit);
                unLock(localKey);
            });
        }
        //返回
        return r;
    }
    public boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    public void unLock(String key){
        stringRedisTemplate.delete(key);
    }

}
